Absolutely brilliant!!! LOVE IT!!!!!!!

As for the solution, hang on:

If the bill was 25, but you guys paid 9 dollars each (27 bucks in total), where are the two extra dollars you paid? And also, she took 2 dollars on top (equalling 29 in total) ... you were well and truly swindled!!! haha ...

Argh!!!!!! She should have given you $1.66 each (5/3), and THEN, if you wanted to tip her, you could have given her the two dollars for her. Thus, $25 + $1.66 x 3 = $30 ... have I solved it? haha.

Regardless, what a song!!!!!!!! From every perspective, loved it - one of the most fun songs I've ever seen on here. Bravo.